![On the Origin of [Ne II] Emission in Young Stars: Mid-Infrared and Optical Observations with the Very Large Telescope](http://data.docslib.org/img/6789d7f659794d8579e7df6f5fc82491-1.webp)
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Ercolano, and Spitzer 0A rmoesd ftesa oteohra ucino wav of function a as other the to star the of side one from AU 10 n 69M¨unchen, Germany 1679 najt ntosas h ml hfsadaymti profil asymmetric and shifts small the stars, two In jet. a in n h trds ytm hs tde ocue htteorig the that concluded studies These system. star-disk the ± ∼ star e ,20610 atClfri olvr,Psdn,C 91125 CA Pasadena, Boulevard, California East 1200 220-6 y, de- a / ABSTRACT UT2 efo X-rays. from ce o ecmaete[eI]ln ihotclfridnlines. forbidden optical with line II] [Ne the compare we ion mnd alets5,C-20Suen,Switzerland Sauverny, CH-1290 51, Maillettes de emin caztas 7 -10Ven,Austria Vienna, A-1180 17, schanzstrasse getn httelnsaeeitdi h aergo.Agen A region. same the in emitted are lines the that uggesting 1 .Te[eI]ln ean neetdi ag ato h sa the of part large a in undetected remains line II] [Ne The y. tar hmndEoi 6 H19 esi,Switzerland Versoix, CH-1290 16, d’Ecogia Chemin 0k s km 80 otmnsrse2 54 acig Germany Garching, 85748 2, Boltzmannstrasse , 2 . tce with etected deo,sosasailyursle iecnee ttes the at centered line unresolved spatially a shows edge-on, ooao ole,C 00-39 USA 80309-0389, CO Boulder, Colorado, - Sosrain,i eea ae,teotclfridnli forbidden optical the cases, several in observations, ES tde aehnstwr h eneitn ehns yexp by mechanism emitting neon the toward hints gave studies ⋆⋆ G¨udel, M. , so sn ihsailadseta eouinobservat resolution spectral and high-spatial using ssion 08,wtr(ar&Njt 08 ay ta.2008; al. emis- G¨udel et al. many et 2009; the Salyk by Among al. detected al et lines et 2011). sion Flaccomio (Pascucci al. 2008; et 2007; species Baldovin-Saavedra 2010; al. atomic et Najita Lahuis and & of Najita (Carr & 2007; 2010), (Carr presence al. molecules disks et the water Pontoppidan organic protoplanetary revealing from of by 2008), lines studies (mid-IR) emission the mid-infrared many to the contribution in large a dis the understand timescales. better dynamics, to size, composition, need its we itself: system, planetary a with f[eI]i h niomn fyugstars: young of interaction environment the the in prese study the II] explain to could [Ne Curr that of disk. used mechanisms the main the is in three and are gas and there irradiation of high-energy disk, diagnostic stellar the good between a of be layer to upper proposed was It interest. ue bandwith obtained fluxes − hVSRVTfr1 tr n VSVTfrtreo them. of three for UVES-VLT and stars 15 for VISIR-VLT th 1 h rgno h N I iei nla n ol ihrbe either could and unclear is line II] [Ne the of origin The . The fimddtcino N I naHri esa,V9 Tau. V892 star, Be Herbig a in II] [Ne of detection nfirmed s–Sas omto tr:pemi sequence pre-main Stars: – formation Stars: – ks 6 , Spitzer 7 Spitzer rsnbtenrslsfo hssuyadprevious and study this from results between arison id rvnb tla X-rays stellar by driven winds 3 rgs K. Briggs, , / R.Tevlct hfsadpolsaeue to used are profiles and shifts velocity The IRS. pc eecp Wre ta.20)made 2004) al. et (Werner Telescope Space Spitzer Spitzer 3 efudn orlto between correlation no found We . eul .M. L. Rebull, , N I 12.81 II] [Ne , rt-lntr ik;isorigin its disks; proto-planetary / U rb h X- the by or EUV no h emission the of in µ 4 kne,S L. S. Skinner, , andparticular gained m sidct an indicate es ⋆ USA eprofiles ne rltrend eral elrrest tellar
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– Irradiated disk atmospheres (Glassgold et al. 2007). In this servations. The stars in our sample are mainly optically thick scenario, the X-rays from the central star create a warm at- disks (Class II). We included a Class I object ( L1551 IRS mosphere composed of gas in atomic form on top of a cooler 5) that has a bright [Ne II] line detected in the Spitzer spec- molecular layer. [Ne II] would be emitted in a region within trum, and an intermediate-mass Herbig Be star ( V892 Tau) be- 20 AU from the central star, the giant planet formation re- cause its low resolution spectrum hinted toward neon emission, gion. but just below the detection threshold (Baldovin-Saavedra et al. – Photoevaporative disk winds driven by EUV (Clarke et al. 2011). The stars known to be jet-driving sources are: CoKu Tau 2001; Alexander et al. 2006), X-rays (Ercolano et al. 2009; 1 (Eisl¨offel & Mundt 1998), XZ Tau (Krist et al. 2008), L1551 Owen et al. 2010) or FUV (Gorti et al. 2009). IRS 5 (Rodr´ıguez et al. 2003), and UY Aur (Hirth et al. 1997). – Shocks (Hollenbach & McKee 1989; Hollenbach & Gorti To our knowledge, the rest of the stars do not have reported out- 2009) and jets (Shang et al. 2010). High velocity outflows flows or jets in the literature. In addition, among the targets se- from the star interacting with the surrounding material lected the following are binaries not resolved by Spitzer: MHO-1 can create strong shocks heating gas to high temperatures. and MHO-2 (3′′. 9 separation, Kraus & Hillenbrand 2009), V892 [Ne II] would be a good tracer of material at velocities Tau (0′′. 05, Smith et al. 2005; Monnier et al. 2008), FS Tau A higher than 40-50 km s−1. (0′′. 24, Hartigan & Kenyon 2003; Hioki et al. 2011), UY Aur (0′′. 88, McCabe et al. 2006), XZ Tau (0′′. 30, Haas et al. 1990), Given the modest spectral resolution of the Spitzer infrared V853 Oph (0′′. 3, McCabe et al. 2006), and CoKu Tau 1 (0′′. 24, spectrograph (IRS; R ∼ 600, i.e., a velocity resolution of ∼ Padgett et al. 1999). Table 1 summarizes the stellar properties of 500 km s−1; Houcketal. 2004) the lines detected are unre- the stars selected for this high-resolution spectroscopy follow- solved. Ground-based observations at high spectral resolution up. are needed in order to determine the origin of the neon-emitting The scope of this study is to obtain high-resolution spectra mechanism, but the number of high-resolution spectra is still of the [Ne II] line (12.81355 µm, Yamada et al. 1985), and by small. Herczeg et al. (2007) detected the [Ne II] emission line determining the line center and studying the profiles, to obtain in one out of three spectra of young circumstellar disks ob- observational constraints on the emission mechanism of [Ne II]. served with the mid-infrared spectrograph on Gemini North The article is organized as follows: in Sect. 2.1 we describe the (R ∼ 30000). Based on the measured linewidth they ruled out VISIR observation strategy and data reduction, in Sect. 2.2 we an accretion flow origin, favoring the photoevaporative theory. present complementary observations obtained in the optical with van Boekel et al. (2009) presented high resolution ground-based UVES-VLT and its data reduction, in Sect. 3 we present the re- spectroscopy (VISIR-VLT) of the young T Tau triplet, succeed- sults, the discussion in Sect. 4, and finally the conclusions in ing in spatially separating the N-S components. These observa- Sect. 5. tions showed that the [Ne II] emission is strongly dominated by outflows heated by shocks. Pascucci & Sterzik (2009) ob- served 6 targets with VISIR-VLT. For 3 stars in the sample, the 2. Observations & Data Reduction line is spectrally resolved, and the line profiles are consistent 2.1. VISIR-VLT with those predicted by photoevaporative flow driven by EUV from the central star. Pascucci et al. (2011) performed an exten- Mid-infrared high-resolution spectra were obtained with the im- sive study on the neon emission in TW Hya using VISIR-VLT. ager and spectrometer VISIR (Lagage et al. 2004), installed at The study confirmed the photoevaporation as emitting mecha- the Melipal telescope (UT3) of the VLT in three runs: May nism of neon in this star. Sacco et al. (2012) also studied the 2009, January 2010, and January 2011. Spectra were obtained origin of [Ne II] emission with VISIR-VLT. They observed a in high-resolution mode (HR) using the long-slit (32′′. 5 long). large sample of young stars and detected the line in 12 out This configuration covers a spectral region between 12.793 and of 32 objects. They concluded that [Ne II] emission originates 12.829 µm. One star (IRS 60) was observed using the cross- mainly in shocks for Class I protostars. This supports the statis- dispersed mode (HRX), that uses a short slit of 4′′. 1, with the tical studies of G¨udel et al. (2010) and Baldovin-Saavedra et al. same spectral coverage. The slit width used was 0′′. 4, achieving (2011) that jets, if present, tend to dominate the [Ne II] emis- a resolving power of ∼ 30000 in both configurations, measured sion. Sacco et al. (2012) also argued that the emission line stems from the FWHM of sky lines present in the spectra, which in from the inner disk (≤ 20 − 40 AU) for stars with transition velocity resolution corresponds to ∼ 10 km s−1. The slit was and pre-transition disks. Their detailed analysis of the line pro- oriented in the default North-South orientation, except for the files indicated an origin from a disk wind, althoughirradiation by sources known to be binaries with a separation such that the sin- EUV/X-rays underestimates the blueshift of the line. Our study gle components could be separated with VISIR. In those cases complements the above studies by providing additional VISIR the slit orientation was adapted in order to obtain the spectra of spectra for 15 targets, mainly Class II stars, and further com- the two componentsof the system. Standard chop-noddingalong paring the [Ne II] line with optical lines, in particular forbidden the slit was applied to correct for mid-infrared background emis- lines such as [O I], [N II], and [S II]. sion with a chop throw between 8′′ and 12′′. Standard giant stars (from the list of Cohen et al. 1999) or an asteroid (Psyche) were observed immediately before or after the science target to cor- 1.1. Sample rect for telluric absorption and to obtain the flux calibration.1 A
We recently studied the gas emission with Spitzer-IRS 1 in a large sample of young stars (G¨udeletal. 2010; In principle, giant stars are not ideal telluric standard stars for medium and high-resolution infrared spectroscopy due to the presence Baldovin-Saavedra et al. 2011) obtaining a large number of de- of photospheric absorption lines, and asteroids are better telluric stan- tections of [Ne II]. For our dedicated VLT-VISIR high-spectral dards. In our case, however, giant stars were sufficient since Ne II detec- resolution study, we selected objects accessible by the VLT tions (before telluric correction) were very strong, as shown in Fig. A.1. for which the line fluxes obtained with Spitzer are higher than Photospheric absorption in giant star spectra are faint, after checking 10−15 erg cm−2 s−1, enough for follow-up ground based ob- with the asteroid spectra. The detections are, therefore, not due to inap-
2 Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations
Table 1. Stellar properties of the sample studied
(h m s) (◦ ′ ′′) a b Name α δ Distance Spectral Type Ref. LX (J2000) (J2000) (pc) (erg s−1) MHO 1 04:14:26.0 +28:06:04.2 140 M2.5 1 1.6 × 1030 MHO 2 04:14:26.4 +28:05:59.7 140 M2.5 1 V892 Tau 04:18:40.7 +28:19:12.3 140 B9 1 9.2 × 1030 CoKu Tau 1 04:18:51.6 +28:20:26.5 140 M0 1 ... FS Tau A 04:22:02.2 +26:57:30.2 140 M0 2 3.2 × 1030 SST042936+243555 04:29:36.2 +24:35:52.5 140 M3 2 ... XZ Tau 04:31:39.8 +18:13:57.3 140 M2 3 9.6 × 1029 L1551 IRS 5 04:31:34.2 +18:08:04.7 140 a Distance compiled in G¨udel et al. (2010) b LX come from G¨udel et al. (2007) or G¨udel et al. (2010) References: (1) Luhman et al. (2010); (2) Rebull et al. (2010); (3) Hartigan & Kenyon (2003); (4) Torres et al. (2006); (5) Luhman (2004); (6) Wilking et al. (2005); (7) Preibisch (1999) summary of the VISIR observations is presented in Table 2, in- iv) The observed calibrator spectrum is corrected for differ- cluding the date of the observations, the exposure time, the mode ences in airmass and air pressure with the science target, follow- (HR high-resolution long-slit or HRX high-resolution cross- ing the procedure described in Carmona et al. (2011). The cali- dispersed), the airmass at the beginning and end of the observa- brator synthetic spectrum is divided by the observed calibrator tions, the seeing in the mid-infrared measured from the FWHM spectrum. This result is then multiplied to the extracted spec- of the continuum,the position angle (following the standard con- trum of the science target to correct for telluric absorption and vention of positive angles in the North-East direction), the star to get an absolute flux calibration. The uncertainty in the flux or asteroid used as calibrator, its respective exposure time, and calibration is of the order of 20 − 30%. airmass. Steps i, ii, and iii were applied to both the science target and The VISIR raw frames were processed with the standard its calibrator. The VISIR spectra were corrected for barycentric VISIR data reduction pipeline version 3.7.2, using the command and radial velocity. line application esorex. The output of the pipeline is a series of Whenever an asteroid was observed to correct for tel- files including the extracted spectrum, a 2D image spectrum, luric absorption, the absolute flux calibration was based in a pixel-to-wavelength map, and a synthetic model spectrum of Spitzer fluxes. In the particular case of UY Aur, the Spitzer flux the calibration star. Starting from the 2D spectrum we have per- corresponds to the binary, therefore to obtain an absolute flux formedfurthersteps based on Boersma et al. (2009) for the spec- calibration for the single components we used in addition the tra obtained in HR mode. flux ratio between the components, derived from high-resolution i) Any remaining backgroundemission is corrected by taking imaging in the N band (McCabe et al. 2006). each pixel row and fitting a second order polynomial, ignoring For the binaries, we converted the separation of the spectra the source power spread function (PSF) profile. The result from from pixels to distance in the sky using the VISIR pixel scale the fit is then subtracted from each pixel row, obtaining a 2D (0′′. 127/pix). The binary systems resolved by our VISIR obser- spectrum that is background-corrected. vations are MHO-1/2, and UY Aur, for which the projected sep- ii) A weight map is created by collapsing the image in the arations observed are consistent with the separations reported dispersion direction, normalizing it, and then expanding it in the in the literature. The small separation of XZ Tau did not allow spatial direction. The science frame is then multiplied by the the system to be spatially resolved, although the observed cross- weight map. The spectrum is obtained by collapsing the result- profile was broad. The CoKu Tau 1 and FS Tau A binaries are ing image in the spatial direction. also not resolved and show cross dispersion profiles consistent with a single source. Observations of EC 92 include the nearby iii) The wavelength calibration is performed using the atmo- ′′ spheric emission lines. This is done by taking a raw frame and star EC 95, located at a distance of 5 , however the spectrum cross-correlating it with a model of the atmospheric spectrum 2. of EC 95 has a very low signal-to-noise ratio and it is not ex- Gaussian profiles are fitted to the atmospheric lines in order to ploitable. obtain accurately the position of their center. By fitting a sec- ond order polynomial the pixel-to-wavelength conversion is ob- 2.2. UVES-VLT tained. This method gives a precision of 0.4 − 0.6kms−1 in the wavelength solution. After the end of our last VISIR run we requested observing time to obtain optical spectra with UVES-VLT for a number of targets propriate telluric correction. Nevertheless, we emphasize that observa- with detected [Ne II] emission in VISIR, under DDT program tions to detect faint Ne II features should ideally be done with asteroids. 286.C-5038(A). The purpose was to derive radial velocities at 2 Available on the VISIR Tools website, see high precision, only possible from high-resolution spectra (see http://www.eso.org/sci/facilities/paranal/instruments details in A.2.1). Radial velocities are obtained by measuring 3 Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations Table 2. Summary of the VISIR observations Name Date ton−source Mode Airmass MIR seeing Pos. Angle Calibrator (Sp. T) tcal Airmass (s) start/end (′′) (◦) (s) MHO 1/2 2011-01-21 1800 HR 1.71/1.89 0.39 −153.8 HD 23319 (K2.5III) 240 1.02 2011-01-23 1800 HR 1.68/1.81 0.33 −153.8 HD 29291 (G8III) 240 1.01 V892 Tau 2010-01-06 3600 HR 1.71/1.70 0.36 0 HD 20644 (K4III) 240 1.69 CoKu Tau 1 2010-01-04 3600 HR 1.72/1.69 0.32 0 HD 17361 (K1.5III) 240 1.70 FS Tau A 2010-01-04 2760 HR 1.73/2.14 0.33 0 HD 27639 (M0III) 240 1.95 2010-01-05 3600 HR 1.71/1.62 0.29 0 HD 27482 (K5III) 240 1.70 SST042936+243555 2011-01-21 1800 HR 1.78/2.17 0.39 0 HD 27639 (M0III) 600 2.46 XZ Tau 2011-01-22 1800 HR 1.52/1.78 0.32 −138.6 Psyche 120 1.85 L1551 IRS 5 2010-01-05 3600 HR 1.41/1.78 0.28 0 HD 27482 (K5III) 240 1.64 UY Aur 2011-01-22 1800 HR 1.76/1.81 0.36 132.4 HD 29291 (G8III) 240 1.00 2011-01-23 1800 HR 1.88/2.14 0.38 132.4 Psyche 120 1.77 VZ Cha 2011-01-22 1800 HR 1.87/1.76 0.32 0 Psyche 120 1.85 RXJ1111.7-7620 2011-01-21 960 HR 1.79/1.74 0.39 0 HD 27639 (M0III) 600 2.46 V853 Oph 2009-06-01 6120 HR 1.01/1.50 0.27 0 HIP 90185 (B9.5III) 600 1.11 IRS 60 2009-05-31 3600 HRX 1.19/1.01 0.40 0 HIP 84012 (A2IV) 840 1.05 2009-06-01 1800 HRX 1.06/1.00 0.40 0 HIP 84012 (A2IV) 480 1.04 EC 92 2009-05-31 4080 HR 1.15/1.18 0.26 −173.7 HIP 99473 (B9.5III) 1200 1.15 2009-06-01 3600 HR 1.36/2.24 0.32 −173.7 HIP 84012 (A2IV) 840 1.38 Table 3. Summary of the UVES observations eral, a correction for the dark current of the CCD is also needed, and this is doneby taking a long exposurewith the shutter closed Name Date Exp. time Airmass Seeing (dark frame). In the case of UVES, the detector dark currents can ′′ (s) ( ) be considered negligible and be excludedfrom the data reduction CoKu Tau 1 2011-03-02 900 2.0 1.4/1.2 process. The wavelength calibration of UVES spectra is done by FS Tau A 2011-03-02 900 2.1 1.2/1.3 using observations of a ThAr lamp and is part of the standard / V853 Oph 2011-03-02 300 1.3 1.3 1.1 procedures of the UVES pipeline. The error in the determina- tion of the wavelength solution is 2 mÅ, typical of the UVES pipeline. The spectra were also corrected for radial and barycen- tric velocity. Given that we did not observe standard stars, the the shift of the absorption lines of the stellar atmosphere with correction for the telluric absorption features and absolute flux respect to a reference spectrum and are crucial to determine the calibration was not possible. However, the data reduction pro- rest velocities of the [Ne II] lines detected with VISIR. UVES cess includes the correction of the spectra for the sky airglow (Ultraviolet and Visual Echelle Spectrograph) is located at the emission. We used the R magnitude and Johnson zero point pho- Nasmyth platform B of the second Unit Telescope (Kueyen) of tometry to determine the flux density in the continuum. the VLT, offers cross-dispersed echelle spectra between 300 up to 1100 nm. The light beam is splitted into two arms; UV-Blue and Visual-Red. These two arms can operate separately or in 3. Results parallel. We used the red arm covering the wavelength range 3.1. [Ne II] detections in VISIR spectra 500 − 595 and 605 − 700 nm. This setting allowed us to cover a region rich in absorption lines, required for the determination The [Ne II] emission line was detected in seven stars in of the stellar radial velocity, and including important emission our sample: MHO-1, V892 Tau, CoKu Tau 1, FS Tau A, lines, such as [O I] and Hα. The slit width used was 1′′. 2, achiev- SST 042936+243555,V853 Oph, and EC 92. The line was fitted ing a resolving power R ∼ 33000. The summary of the observa- using a Gaussian profile plus a linear component to account for tions is presented in Table 3. the continuum. All the parameters of the function were left free We reduced the data following the standard UVES pipeline to vary. For the cases with non detections, an estimation of the recipes, version 4.9.0, using the command line application es- upper limit was calculated as three times the standard deviation orex. Optical data need to be corrected for several instrumental of the continuum flux (σ) times the spectrograph full width half effects. To correct for the electronic noise of the camera and pos- maximum (FWHM). Figure 1 displays the spectra after wave- sible systematics, a short exposure (bias) is taken with the shut- length and flux calibration, plotted including the error bars in ter closed; the bias frames give the read out of the CCD detector the flux. The green line represents the Gaussian fit, and the red for zero integration time. Several bias frames are combined into dot-dashed line is the 3σ upper limit threshold. The spectra are a master bias; in the case of UVES five bias frames are taken. plotted in the stellocentric frame; the vertical dashed line shows The more bias exposures are taken, the less noise will be intro- the position the lines would have if centered at the stellar ra- duced into the corrected images. Furthermore, as the telescope dial velocity. The figure was divided in two panels: detections does not illuminate the detector homogeneously, and the quan- in the upper panel and non detections in the lower one. In addi- tum efficiency of the CCD is not necessarily the same over all the tion, the detections are separated in two groups: stars showing pixels, an exposure of an homogeneously illuminated area (flat a line blueshifted to high velocities, and stars with a line nearly field) needs to be taken. Five flat fields are then combinedto cre- centered or shifted by a few km s−1. Figure A.1 displays the ate the normalized master flat field for UVES observations. The observed spectra of the stars and its telluric standard before ap- bias frame is subtracted of each raw science frame and the resul- plying any velocity correction. Only one data set is included for tant spectrum is divided by the master flat field frame. In gen- the stars observed in two different days. 4 Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations 0.6 MHO-1 SST042936+243555 0.5 V853 Oph EC 92 1.4 0.5 1.4 0.4 0.4 1.2 1.2 0.3 0.3 1.0 Flux (Jy) 1.0 0.2 0.1 0.8 0.8 0.2 0.0 40 V892 Tau CoKu Tau 1 1.4 FS Tau A 1.2 1.2 35 1.0 1.0 30 0.8 Flux (Jy) 0.8 0.6 25 0.6 0.4 0.40 MHO-2 4.5 XZ Tau L1551 IRS 5 UY Aur A 1.8 9 0.35 4.0 1.6 0.30 3.5 8 1.4 Flux (Jy) 0.25 3.0 7 1.2 0.20 2.5 6 1.0 1.1 UY Aur B VZ Cha 0.6 RXJ1111.7-7620 IRS 60 0.7 0.8 1.0 0.5 0.6 0.7 0.4 0.9 0.5 0.6 0.3 0.4 0.8 0.5 Flux (Jy) 0.2 0.3 0.7 0.1 0.4 0.2 0.0 0.3 0.6 0.1 -100 0 100 -100 0 100 -100 0 100 -100 0 100 v (km s-1 ) v (km s-1 ) v (km s-1 ) v (km s-1 ) Fig. 1. Spectra of the stars observed with VISIR plotted in stellocentric frame and rebinned by a factor of two (average spectra are shown when there are more than one observations). The detections are plotted in the upper panel, non detections in the lower one. The green line is the Gaussian fit to the line, the red dot-dashed line is the 3σ detection threshold per pixel. The error bars shown are 1σ values per pixel. Table 4 shows the results obtained from the fits to the sion from an intermediate mass pre-main sequence star. The [Ne II] emission line: the integrated line fluxes or upper limits [Ne II] line is detected close to the stellar rest velocity in three in Col. 2, the FWHM of the detected lines in Col. 4, and the cen- cases: CoKu Tau 1, FS Tau A, and V892 Tau. For them, we stud- ter of the Gaussian in Col. 5. In addition, we report the Spitzer ied the symmetry of the line profiles by using the procedure de- fluxes for comparison in Col. 3, the stellar radial velocity and its scribed in Pascucci et al. (2011); each line is flipped and shifted reference in Cols. 6 and 7, respectively. The errors of the mea- in wavelength direction to get a good match with the original surements are reported between parentheses. profile. The two profiles are then subtracted and the result is plotted; the more symmetric the line, the closer to zero the dif- The detection of [Ne II] from the Herbig Be star V892 ference. The results are shown in Figure 2: in the upper panel Tau that we present here is the first report of [Ne II] emis- 5 Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations Table 4. Results for the [Ne II] line obtained from the VISIR spectra. The peak is given in the stellocentric frame. Errors are reported between parentheses. [1] [2] [3] [4] [5] [6] [7] Name Flux Spitzer Flux ♣ FWHM Peak† vrad vrad Ref. (10−15 erg cm−2 s−1) (10−15 erg cm−2 s−1) (km s−1) (km s−1) (km s−1) Detected lines MHO 1 8.0 (1.5) 120 ♦ 26.7 (3.3) −121.8 (6.6) 16.0 (6.4)♠ Bertout & Genova (2006) V892 Tau 179 (16) < 180 26.0 (3.4) −2.13 (6.5) 16.0 (6.4)♠ Bertout & Genova (2006) CoKu Tau 1 20.4 (2.5) 120 55.2 (3.3) 3.6 (1.5) 15.0 (0.8) White & Hillenbrand (2004) FS Tau A 16.6 (1.7) 77 26.8 (1.7) −2.9 (0.7) 17.1 (0.1) This work SST042936+243555 7.8 (1.7) 11 26.0 (3.8) −89.1 (6.6) 16.0 (6.4)♠ Bertout & Genova (2006) V853 Oph 3.7 (0.8) 16 26.5 (3.9) −35.8 (1.6) −8.9 (0.1) This work EC 92 4.2 (1.2) 15 16.2 (4.3) −31.3 (2.3) −7.1 (1.5) Covey et al. (2006) Upper limits MHO 2 < 0.5 120 ♦ ...... 16.0 (6.4)♠ Bertout & Genova (2006) XZ Tau < 5.2 32 ...... 17 (7) Folha & Emerson (2000) L1551 IRS 5 < 4.3 580 ...... 8.2 (1.5) Covey et al. (2006) UY Aur A < 2.4 49 ♦ ...... 18 (3) Barbier-Brossat & Figon (1999) UY Aur B < 1.2 49 ♦ ...... 18 (3) Barbier-Brossat & Figon (1999) VZ Cha < 2.3 3.8 ...... 19.0 (1.7) Torres et al. (2006) RXJ1111.7-7620 < 3.3 5.1 ...... 15.5 (0.3) Torres et al. (2006) IRS 60 < 1.6 14 ...... −2.2 Torres et al. (2006) ♣ Spitzer fluxes come from G¨udel et al. (2010) or Baldovin-Saavedra et al. (2011) † The error in the center was calculated considering the contribution of the error in the Gaussian fit and in the stellar radial velocity ♠ In these cases there is no radial velocity in the literature, the average radial velocity of Taurus was assumed. ♦ The binary systems UY Aur (A,B) and MHO 1/2 cannot be separated in the Spitzer spectrum, therefore the flux reported is for the system. of the figure, the original and the flipped spectrum are shown, 3.1.1. Comparison with Spitzer line fluxes while the lower panel displays the difference between both pro- files. This method does not show any evident asymmetry in the We now compare the line fluxes obtained with VISIR with the line profiles. fluxes obtained previously from Spitzer low-resolution spectra. In general, VISIR fluxes tend to be lower than Spitzer fluxes (reported in Table 4 column 3). Focusing only on the detected lines, we found that in one case (V892 Tau) the flux obtained The spatial extent of the emission can be quantified by sub- with VISIR corresponds to the Spitzer upper limit. The differ- tracting the average PSF observed in the continuum from the ence between Spitzer and VISIR fluxes can go as high as one 2D spectrum, as presented in the position velocity diagrams in order of magnitude. In the case of MHO 1/2, the Spitzer flux Figure 3 (contours start at 3σ with an increase of 5σ at each reported is for the unresolved binary, but the [Ne II] line was de- step), bearing in mind the limited spatial resolution imposed by tected only in MHO 1 with VISIR. We found that for FS Tau A the instrumental PSF. CoKu Tau 1 presents symmetric emission and SST042936+243555the VISIR flux is between 30 and 40% centered at the stellar rest velocity, with no extended emission lower than the Spitzer flux. For CoKu Tau 1, V853 Oph, and beyond the 0′′. 3 (40 AU at the distance of Taurus) spatial reso- EC 92 the difference between Spitzer and VISIR fluxes are high, lution of the VLT in the mid-infrared. The average PSF in the the flux obtained with VISIR observations represent between continuum is also consistent with a point source, indicating that 20 − 30% of the Spitzer flux. The variation between Spitzer the 0′′. 24 companion (Padgett et al. 1999) was not detected. The and VISIR fluxes has been previously reported by Pascucci et al. centroid of the emission at negative velocities is slightly dis- (2011), where they found on the order of 30% for TW Hya. placed to “negative” spatial extension (about 10 AU) whereas Sacco et al. (2012) also found evidence of the flux discrepan- the centroid at positive velocities goes to “positive” spatial ex- cies in their targets for Class I and Class II stars, arguing that tension (also about 10 AU). This could be a signature of disk the [Ne II] emission is extended at least in Class I stars, and rotation, but considering the fact that the slit was oriented with partially in Class II stars. However, they found flux ratios be- PA=0◦, i.e., close to the direction of the bipolar jet (PA=210◦), tween Spitzer and VISIR that are consistent within a factor of 2 the centroid’s displacement could also reflect emission by the for pre-transition and transition disks, suggesting that the emis- bipolar jet. We address this point in the discussion (Section 4.1). sion is produced close to the star, within ∼ 20 − 40 AU. In our The emission from FS Tau A is centered at negative velocities, study, the reason for the observed variation remains unclear, al- with evidence of extension toward negative velocities, indica- though plausible but unlikely explanations might be unidenti- tion of photoevaporative wind. The symmetry of the emission fied flux calibration issues, slit losses in VISIR observations due is much less evident than in CoKu Tau 1. The 3σ level extends to an incorrect centering of a star in the slit, unexpected tele- up to velocities of ±40 km s−1. The [Ne II] PV diagram in FS scope drifts, or to atmospheric conditions. A faint, very broad Tau A suggests some extended emission beyond 0′′. 3 that cannot line could also remain undetected. The most likely explanation be attributed to the close 0′′. 24 companion (Hartigan & Kenyon for the flux discrepancies is the different beam sizes between 2003). The [Ne II] emission from V892 Tau shows an extension Spitzer and VISIR that translate into possible extended emission toward the blue side of the spectrum. Its PV diagram also indi- unresolved and detected in Spitzer but undetected with VISIR. cates extended emission beyond 0′′. 3. Indeed, Spitzer spectra are extracted from a region covering the 6 Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations CoKu Tau 1 FS Tau A V892 Tau [Ne II] [Ne II] [Ne II] 1.0 0 Normalized Flux 0.4 0.0 Difference -0.4 -50 0 50 -50 0 50 -50 0 50 v (km s-1 ) v (km s-1 ) v (km s-1 ) Fig. 2. Upper panel: Plotted as grey filled area the profile of the [Ne II] line and in red solid line the profile flipped. Lower panel: Difference between the original and the flipped profile. CoKu Tau 1 FS Tau A V892 Tau 1.2 1.2 36 1.0 0.8 32 0.8 Flux (Jy) Flux (Jy) Flux (Jy) 28 0.6 0.4 0.3 50 0.3 50 0.3 50 0.0 0 0.0 0 0.0 0 AU AU AU -0.3 -50 -0.3 -50 -0.3 -50 Spat. Extension (") Spat. Extension (") Spat. Extension (") -50 0 50 -40 -20 0 20 40 -40 -20 0 20 40 v (km/s) v (km/s) v (km/s) Fig. 3. Upper panels: Observed VISIR spectrum of CoKu Tau 1, FS Tau A, and V892 Tau. Lower panels: Position velocity diagrams after subtraction of the continuum PSF. The contour levels start at 3σ and increase with a step of 5σ. The PSF FWHM is ≈ 0′′. 3. whole slit width, for IRS high-resolution this means a region of originates in the outflow, at distances larger than ≈ 0′′. 4 from the ∼ 11′′, i.e., about 1500 AU at 140 pc. central star, although the short integration in the acquisition im- We note that L1551 IRS5 was selected for this program be- age did not allow the detection of extended emission. We did not cause a bright [Ne II] line was detected in the Spitzer spectrum, repeat the observations at a different P.A. because the outflow withafluxof5.8×10−13 erg s−1 cm−2, i.e., a luminosity of the or- explanation is the most likely in this case. 30 −1 der of L[Ne II] ∼ 10 erg s . Although the line was not detected in spectroscopy mode, the target was detected in the [Ne II] nar- 3.2. Optical emission lines detected in UVES spectra row band image, likely due to the strong continuum emission. This Class I star is known to drive a highly collimated bipo- Low-excitation forbidden lines are used as diagnostics lar outflow observed in the optical, near-infrared and radio (e.g., of the physical conditions of the gas in the wind and Davis et al. 2003; Pyo et al. 2009; Wu et al. 2009). The position shock environments of T Tauri stars (e.g. Hamann 1994; angle of the outflow is measured at 260◦ for the northern compo- Gomezde Castro & Pudritz 1993; Ouyed& Pudritz 1994). nent and 235◦ for the southern component (Pyo et al. 2009). The For example, the ratio [SII]λ6716/[S II]λ6730 is strongly ◦ VISIR observations were performed with a P.A.= 0 . The non- dependent on the electron density ne, while the ratios detection of [Ne II] in the spectrum suggests that the emission [S II]λ6730/[OI]λ6300 and [NII]λ6584/[OI]λ6300 are 7 Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations ◦ dependent on the electron temperature, Te. The [O I] λ6300 line face-on (inclination angle i = 0 ) showed a single peaked line is usually observed in T Tauri spectra (e.g., Cabrit et al. 1990), blueshifted by typically < 10 km s−1. On the other hand, a disk often exhibiting a broad high velocity component blueshifted up viewed edge-on (i = 90◦) showed a double-peaked profile. The to several hundred km s−1 (HVC) and a low-velocity component emission is expected to be centered at the stellar velocity with (LVC) which is narrower and blueshifted by only a few km s−1 one peak blueshifted and the other redshifted. The line widths (see e.g., Hartigan et al. 1995). The LVC and HVC are thought predicted are FWHM ∼ 10 km s−1 for the face-on case and to have different origins; the HVC is believed to be tracing a jet, FWHM ∼ 30 km s−1 for the edge-on case. In addition, a disk while the LVC is interpreted as a tracer of a photoevaporative with an inner hole of 9 AU (in both dust and gas) is also mod- disk wind by Ercolano & Owen (2010). In particular, these eled. For the face-on case, the line width and shift are equiva- authors proposed the presence of both [Ne II] and [O I] as an lent to the disk without an inner hole. In the edge-on case, the indicator of an X-ray photoevaporative disk wind. Permitted line was narrower for the model with an inner hole than for the emission lines of Fe II are also observed in the optical. For model without an inner hole (FWHM ∼ 20 km s−1). In addi- example, Beristain et al. (1998) found line profiles showing a tion, the line was double peaked and centered at the stellar rest narrow and a broad component that were interpreted as being velocity. A narrower line is in fact expected since the material produced by different kinematic zones: the narrow component closer to the star has larger rotational velocity and gives rise to is produced by turbulence and broadened by stellar rotation, the broadening of the line. originating in gas located in the post-shock region, and the Ercolano & Owen (2010) considered the photoevaporation broad component is produced in gas infalling in the accretion of the disk driven by EUV and X-rays and modeled the pro- funnel. Furthermore, He I emission lines are presented as a files for a series of emission lines, putting special attention on powerful diagnostics, because their high excitation potential the [NeII]and[O I](λ6300). The model considered a disk with and emission is restricted to regions of high temperature or close to without inner holes of 9, 14, and 30 AU at different inclination the ionizing source (Beristain et al. 2001). angles between 0◦ and 90◦. Furthermore, the X-ray luminosity The optical spectra obtained with UVES show several of was also variable between log(LX) = 28.3 to log(LX) = 30.3. these emission lines, whose profiles can be compared with the The profile of the [Ne II] line for the modelwithoutan innerhole profile of the [Ne II] line from VISIR to understand the circum- varied according to the disk inclination. A face-on disk showed stellar environmentof the sources and provide hints on the origin a narrow profile, with a FWHM between ∼ 4 km s−1 for low −1 of the [Ne II] lines observed. In Table 5 we present the proper- LX and ∼ 10 km s for high LX. For the edge-on case, the line ties of the optical lines detected in the spectra of CoKu Tau 1, profiles are larger but do not change much with LX; the FWHM FS Tau A, and V853 Oph. In the second column we include the are between ∼ 20 km s−1 and ∼ 23 km s−1 for the low and rest wavelength of the lines taken from the NIST Atomic Spectra high LX, respectively. Only in the case of a face-on disk and 3 Database . The line center with respect to the systemic velocity low LX was the line found to be centered at the stellar velocity; of the star, and FWHM (Cols. 3 and 4) were obtained by fit- in all other cases the line was blueshifted by up to ∼ 5kms−1. ting a Gaussian profile to the lines, and the errors reported come All the profiles obtained were asymmetric, with a shoulder to- from the fit. The line fluxes (Col. 5) were calculated using as ward the blueshifted part, which became more evident for the continuum the stellar flux derived from the R magnitude and the high LX model. Johnson zero point photometry. In Col. 6 we present the equiva- Using the predictions of such models we can attempt to give lent widths (EW) calculated by integrating the line fluxes within an interpretation to the line profiles observed. Following the or- 3σ of the Gaussian fit. der of the panels of Fig. 1 we can identify three regimes for the [Ne II] emission: Highly blueshifted [Ne II] emission from jets: The line pro- 4. Discussion files shown in the upper panel of Fig. 1 correspond to this group and they are characterized by a large velocity shift toward the 4.1. Origin of [Ne II] emission: observations and models blue. The emission is likely to originate mainly from shocks in The emission of [Ne II] from protoplanetary disks has been jets. For MHO-1 and SST 042936+243555 there is no available discussed in a series of articles that model the irradiation of measurement of the radial velocity (we assumed the average ra- the disk by high energy photons, each of them gives a differ- dial velocity of the Taurus Molecular Cloud) but since they are −1 ent possible scenario for the formation of this emission line observed with high velocity shifts, −122 and −89kms respec- (see Glassgold et al. 2007; Alexander 2008; Gorti & Hollenbach tively, we conclude that the emission is likely originating in a jet. 2008; Ercolano & Owen 2010). Observations at high spectral V853 Oph and EC 92 also likely belong to this group, with ve- −1 and spatial resolution provide line profiles and shifts that can locity shifts of −36 and −31kms respectively, despite the low be used to test the different models. peak velocities, perhaps due to inclination effects. Glassgold et al. (2007) predicted [Ne II] emission from an There is no record in the literature of jets detected in our X-ray irradiated disk atmosphere.In this model, the [Ne II] emis- sample of stars with highly blueshifted [Ne II] emission. In the sion comes from a region within 20 AU from the star. The pre- case of SST 042936+243555,this is likely due to the low num- dicted line profile is double peaked with extended wings asso- ber of observations dedicated to look for jet or outflow emission ciated with material at small radii, although the authors did not published. From a search in the literature, spectroscopic obser- give any estimates of the line widths expected. vations in the optical or in the near-infrared do not show any Alexander (2008) modeled the [Ne II] line profiles from evidence of outflow or jet emission in MHO-1, V853 Oph, or a photoevaporative disk wind driven by stellar EUV photons, EC 92. assuming a spectral resolution of R ∼ 30000. The model in- Shangetal. (2010) modeled the profiles of [Ne II] and cluded different disk inclination angles. The line profiles ob- [OI](λ6300) expected from a jet. The centroid of the lines show −1 tained varied with the disk inclination considered. A disk viewed a large shift toward the blue, reaching −200 km s , for an in- clination angle of 45◦. The lines are asymmetric with a broad 3 http://physics.nist.gov/ shoulder toward the red side of the spectrum. The excess emis- 8 Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations sion toward the red can reach up to +100 km s−1, depending on 4.2. Comparison between [Ne II] profile and optical lines the inclination angle. The profiles of the model were calculated for a resolution of 1 km s−1, much higher than the resolution We can further compare the profiles of the [Ne II] line with the achieved with our VISIR observations. However, the dominant profiles of the optical lines for the three targets observed in our feature is a large blue-shifted peak, like observed in MHO-1, UVES program. Figures 4, 5, and 6 show in black line and grey SST 042936+243555,V853 Oph, and EC 92. area the profile of the [Ne II] line and in red the profile of the optical lines detected. The spectra were continuum subtracted and normalized to the peak of the line to allow comparison. Weakly blueshifted [Ne II] emission from photoevaporative wind: The centroids of the lines in this category are close to the – CoKu Tau 1 stellar rest velocity or show a small velocity shift. To this group belong FS Tau A and V892 Tau. In particular, the [Ne II] pro- The profiles of the optical forbidden lines are generally com- file from V892 Tau shows an excess toward the blue, and a line patible with the profile of the [Ne II] line, i.e., similar center widthof25kms−1. Thestar is knowntobea binaryofseparation and FWHM. The [N II] lines are slightly broader than [Ne II], ∼ 5 AU. The circumbinary disk was detected by Monnier et al. in contrast to the [O I] and [S II] lines which are of similar (2008) through infrared imaging. The inclination of the disk is width (or slightly smaller in the case of oxygen). The Hα line estimated to be i = 60◦ and the disk inner hole to be ∼ 35 AU. is much broader, possibly tracing additional regions than the FS Tau A is also a close binary system, with separation 0′′. 24 optical forbidden lines. The Fe II line (λ6432) is also much −1 (Hartigan & Kenyon 2003, equivalent to 34 AU at the distance broader (FWHM ∼ 250 km s ). The optical forbidden lines of Taurus) and surrounded by a circumbinary disk that extends are only shown in Figure 4, whereas the Fe II and Hα lines ap- up to 630 AU (Hioki et al. 2011). The spatial extension of the pear in the Appendix (Fig. A.2). The shapes of the two detected emission (Figure 3) in both systems shows an excess toward the [N II] lines (λ6548 and λ6583) are more difficult to interpret, blue side of the spectrum, i.e., an indication of a photoevapora- they appear double or multiply peaked but this might also be tive disk wind. due to a lower signal-to-noise ratio in that part of the spectrum. We note that the optical line profiles are compatible with those of White & Hillenbrand (2004) from HIRES data. The optical The special case of CoKu Tau 1: The emission line de- emission spectrum is completely dominated by optical forbid- tected in CoKu Tau 1 shows a flat-topped, broad profile with den lines (and Hα), which is typically seen in edge-on Class I −1 a FWHM of 55 km s , and wings extending up to velocities stars (White & Hillenbrand 2004). The origin of these optical − close to ±80 km s 1. The emission is also spatially unresolved. lines is unclear but could either be due to the disk atmosphereor The immediate interpretation is that the [Ne II] line originates from the inner bipolar jet. The profile of the [Ne II] line is con- from the disk atmosphere, from material located at small disk sistent with the forbidden lines (Fig. 3), which suggests that the radii. However, the star is known to be viewed close to edge-on line may either originate from the same region. In the bipolar jet ◦ (i = 87 , Robitaille et al. 2007) and is known to have a bipolar jet interpretation, the broader [N II] lines may include a faster com- detected at both positive and negative velocities relative to the ponent, possibly because they would form closer to the faster jet star (Movsesyan & Magakyan 1989; Eisl¨offel & Mundt 1998). axis, whereas the [O I], [S II], and [Ne II] lines form closer to Photoevaporation models at nearly edge-on inclinations predict the slower jet surface. The comparison of the optical forbidden large wings, but due to model construction they never extend lines and the [Ne II] line does not allow to determine conclu- − beyond ±40 km s 1 (e.g., Alexander 2008; Ercolano & Owen sively the origin of the lines, although the bipolar jet origin is 2010). Perhaps a fast photoevaporative wind could explain the the most likely one. broaderwings observed in CoKu Tau 1. Bast et al. (2011) argued also that broad centrally peaked CO line profiles in protoplane- – FS Tau A tary disks could not be explained by inclined disks in Keplerian rotation, but that a combination of emission from the inner part Theprofile ofthe [Ne II]line in FS Tau A is generallysimilar of the disk and a slow moving disk wind could explain the line to the profiles of the optical forbiddenlines, and to He I (λ5876; profiles. Although the disk interpretation for CoKu Tau 1 is more the line is, however, broader) and Fe II (λ5197; the line is red- physically interesting, the bipolar jet explanation is as valid: first, shifted with respect to [Ne II] and the stellar radial velocity). The its [Ne II] flux is rather high with Spitzer and VISIR and is more optical forbidden lines are nearly centered at the stellar radial typical of fluxes detected from jets. Second, although the PV velocity or slightly blueshifted with a FWHM ∼ 30 km s−1. The diagram shows spatially unresolved emission, a careful analy- profiles are consistent with a photoevaporative wind flow, like sis indicates peaks at “negative” spatial extension for negative the ones modeled by Ercolano & Owen (2010), nearly centered velocities, and peaks at “positive” spatial extension for positive with a shoulder toward blueshifted velocities. This blueshifted velocities. Considering the fact that we used a NS slit orientation shoulder is larger for [N II] (λ6583). The observed line pro- with VISIR (and UVES) while the jet is oriented with PA=210◦ files are consistent with the modeled profiles considering the with positive velocities toward the South (and inversely for the disk inclination, estimated at i = 30 − 40◦ (Hioki et al. 2011). counterjet; Eisl¨offel & Mundt 1998), the centroids of the [Ne II] Furthermore, the presence of [Ne II] and [O I] are indica- peaks are consistent with the bipolar jet interpretation. On the tions of an X-ray driven photoevaporative flow, according to other hand the direction of rotation of the disk in CoKu Tau 1 is Ercolano & Owen (2010). In fact, the low-velocity component unknown, and the [Ne II] peaks could also trace this rotation. In of the [O I] line can only be reproduced in the presence of fact, the peaks extend up to ±10 AU. In conclusion, the origin of X-rays. A comparison with the profile modeled by Alexander [Ne II] emission in CoKu Tau 1 is difficult to ascertain and could (2008) is more difficult since only the profiles for the edge-on be either from the disk atmosphere or from the bipolar jet, with a and face-on disks are shown. Nevertheless the FWHM for the possible contribution by a photoevaporativewind. A comparison case i = 45◦ is reported and is compatible with the value de- −1 with the optical forbidden line (see below) does not allow us to rived from the observations: FWHMmodel= 28 km s versus −1 constrain better the origin of the [Ne II] line. FWHMobs= 27 km s . 9 Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations CoKu Tau 1 [N II] 6548 [N II] 6583 [O I] 6300 1.0 [Ne II] [Ne II] [Ne II] 0 Normalized Flux [O I] 6363 [S II] 6716 [S II] 6730 1.0 [Ne II] [Ne II] [Ne II] 0 Normalized Flux -100 0 100 -100 0 100 -100 0 100 v (km s-1 ) v (km s-1 ) v (km s-1 ) Fig. 4. Lines detected in the UVES spectrum of CoKu Tau 1 plotted as a filled grey area compared to the profile of [Ne II] (red line). The spectra were continuum subtracted and normalized to the peak of the lines to allow comparison. – V853 Oph rected with observations of a telluric standard. Since we do not have a telluric calibrator for the optical spectra, we used archival V853 Oph shows a [Ne II] line blueshifted by 36 km s−1, spectra of early type stars to look for contamination of atmo- with a FWHM = 26 km s−1. The large velocity shift observed spheric absorption lines in the profile of [O I]. There is, indeed, suggest that the line is emitted by a jet. In this star, the profiles a 20-30 % absorption feature at the proper position, suggesting of the optical lines are not always compatible with the profile of that some but not all of the absorption feature observed in the the [Ne II] line; we can classify them according to their shifts λ6300 line is due to a water absorption line. and widths: Lines emitted in a jet: these are the [N II] (λ6583) and the Lines emitted by the star or the disk: These are He I [S II] lines, and the high-velocity component of the [O I] λ6300 (λ5015, 5876, 6678)and Fe II (λ5018, 5169). They show differ- line. The [S II] (λ6730) line matches the [Ne II] profile, with ent shapes; the He I lines are asymmetric with an excess toward similar center and FWHM, whereas the [N II] line is slightly redshifted emission, while the Fe II lines are well centered and broader and shows emission at higher speeds, but the signal-to- narrow. noise ratio is not large. The line profiles differ from the pro- Lines compatible with photoevaporation: These are [O I] files predicted by Shang et al. (2010); they are narrow and the (λ5577, 6300, 6363). The [O I] lines show different shapes; the peak is located at velocities lower than predicted by the model; −1 −1 λ5577 line is fairly well centered at the stellar rest velocity and −37 kms against ∼ 100 − 200 km s . shows the blue shoulder typical of photoevaporative wind flows, In conclusion, at least in the case of V853 Oph, the detected and is also compatible with the disk inclination angle (i = 32◦, [Ne II] line is not a tracer of photoevaporativewindsince it traces Andrews et al. 2010). The λ6300 line, on the other hand, shows a high-velocity component of a jet. Possibly the [Ne II] compo- two velocity components: one close to the stellar rest velocity nent from a photoevaporative wind exists, but it is much fainter and the other with a higher velocity shift toward the blue, prob- than the jet component detected with Spitzer and VISIR. ably due to a jet. The separation between the components are believed to be real, although there is likely a moderate absorp- 4.3. Summary of [Ne II] ground based observations. tion between the components due to water molecular absorption. Indeed, although oxygen emission lines are present in the sky Putting together previous results (Herczegetal. 2007; spectrum, they are removed in the data reduction process. But van Boekel et al. 2009; Najita et al. 2009; Pascucci & Sterzik molecular absorption lines from the atmosphere can only be cor- 2009; Pascucci et al. 2011; Sacco et al. 2012) with the ones 10 Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations FS Tau A He I 5876 [N II] 6548 [N II] 6583 1.0 [Ne II] [Ne II] [Ne II] 0 Normalized Flux [O I] 5577 [O I] 6300 [O I] 6363 1.0 [Ne II] [Ne II] [Ne II] 0 Normalized Flux [S II] 6716 [S II] 6730 Fe II 5197 1.0 [Ne II] [Ne II] [Ne II] 0 Normalized Flux -100 0 100 -100 0 100 -100 0 100 v (km s-1 ) v (km s-1 ) v (km s-1 ) Fig. 5. Profile of the optical lines detected with UVES and the profile of the [Ne II] line for FS Tau A. The color code used is the same as Fig. 4. from our program, there is a sample of 26 objects, for which is expected if X-rays are responsible for the neon emission. [Ne II] emission is detected from the ground with high spectral Sacco et al. (2012) found no obvious correlation between the resolution to derive the kinematics of the [Ne II] emission. The [Ne II] and X-ray luminosities in their sample. Restricting to study by Sacco et al. (2012), published while this paper was all detected sources in which ground based observations givea being refereed, provided 12 new detections among 32 targets line consistent with disk emission and the ones consistent with and was able to provide some conclusions about the origin photoevaporation, there is still no clear evidence of a trend. But, of [Ne II] emission, in particular for Class I sources and for if dropping the 5 targets in Sacco et al. (2012) with an observed transition and pre-transition disk sources. Our study focusses blueshift less than 18 km s−1 and whose disk inclinations are more on Class II stars and provides additional comparison of unknown, there is a possible trend for higher neon luminosities the [Ne II] line emission with high-resolution optical lines, with higher X-ray luminosities. However, we emphasize that in particular forbidden lines such as [O I], [S II]. We can the sample is relatively small, and there are many uncertainties attempt to extract some general conclusions from the results (classification, inclination, variability, etc). we have in hand up to now, keeping in mind that ground based observations are challenging in terms of sensitivity. Studies Another lesson from Spitzer observations is that bright neon based on Spitzer observations showed a weak correlation emission is expected in jet sources, and that whenever jets between the [Ne II] luminosity and the X-ray luminosity, in are present, they dominate over the disk emission (G¨udel et al. particular for optically thick disks sources. This correlation 2010; Baldovin-Saavedra et al. 2011). Ground-based observa- tions have shown that jets are significant emitters of [Ne II] line 11 Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations V853 Oph He I 5015 He I 5876 He I 6678 1.0 [Ne II] [Ne II] [Ne II] 0 Normalized Flux [N II] 6583 [O I] 5577 [O I] 6300 1.0 [Ne II] [Ne II] [Ne II] 0 Normalized Flux [O I] 6363 [S II] 6730 Fe II 5018 1.0 [Ne II] [Ne II] [Ne II] 0 Normalized Flux Fe II 5169 -100 0 100 -100 0 100 1.0 [Ne II] v (km s-1 ) v (km s-1 ) 0 Normalized Flux -100 0 100 v (km s-1 ) Fig. 6. Profile of the optical lines detected with UVES and the profile of the [Ne II] line in V853 Oph. The color code used is the same as Fig. 4. emission (e.g., van Boekel et al. 2009, Pascucci & Sterzik 2009, pre-main sequence stars and to their accretion history. Outflows Sacco et al. 2012, this work). The detected lines in jet sources and jets are more powerful during the earlier stages and they tend to be fainter than lines compatible with disk or slow wind tend to decrease in intensity as the star evolves toward a state emission (see also Fig. 4 in Sacco et al. 2012). This can be ex- of lower level of accretion. Unfortunately, there is little informa- plained because the larger beam of Spitzer was able to capture tion in the literature about the stars of the sample showing neon most of the extended emission produced by shocks, but this emission consistent with outflows/jets. They are generally clas- emission is filtered out by the narrow slit used in ground based sified as Class II sources, and the levels of disk mass accretion observations. Jet activity is closely related to the evolution of 12 Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations −8 −1 rate are in the typical level of T Tauri stars (∼ 10 M⊙ yr ; e.g., disk emission. It may, nevertheless, be that photoevaporation is G¨udel et al. 2007; G¨udel et al. 2010, and references therein). the most efficient mechanism for [Ne II] emission in transition Sacco et al. (2012) also argue that the ratio between [Ne II] and pre-transition disk sources, as argued by Sacco et al. (2012). fluxes measured by Spitzer and VISIR are consistent for transi- Disk emission appears, on the other hand, rare and subject to tion disk and pre-transition disk sources. Our detected sample uncertainties such as the disk inclination. does not include targets with such a classification, but Class II stars (except V892 Tau) that show VISIR fluxes several times lower than Spitzer fluxes, consistently with the Class II stars ob- 5. Summary and Conclusions served by Sacco et al. (2012). The latter argued that the emission We presented observations of the [Ne II] line at 12.81 µm at in transition and pre-transition disk objects would be located high spectral and spatial resolution obtained with VISIR-VLT within a few AU from the central star, in contrast with Class II in a sample of selected pre-main sequence stars with previously sourcesthat would emit [Ne II] from both the inner region and an detected neon emission with Spitzer. The emission line was de- extended envelope. In our three targets with low velocity shifts, tected and spectrally resolved in seven stars. We interpreted the extended emission is found for both FS Tau A and V892 Tau, profiles and shifts according to three emitting mechanisms: whereas CoKu Tau 1 shows no evidence of extended emission (but its emission is either due to a bipolar jet or a disk). Thus, – Lines consistent with photoevaporation. These are the lines overall, our data support the interpretation by Sacco et al. (2012) detected in FS Tau A and the Herbig Be star V892 Tau. that extended emission is present in some Class II sources. They show small shifts with respect to the stellar velocity In three stars the [Ne II] line could be interpreted with and FWHM ∼ 26 km s−1. disk emission: CoKu Tau 1 (this work), AA Tau, and GM Aur – Lines consistent with shocked material in outflows/jet. The (Najita et al. 2009). The first two are classical optically thick line centroids are blueshifted at large velocities in four stars: disks and GM Aur is a more evolved transitional disk. The first MHO-1, SST042936+243555,V853 Oph,and EC 92.To our two also have high inclination angles: i = 87◦ ( CoKu Tau 1; knowledge,there is no previousrecord in the literature of the Robitaille et al. 2007) and i = 75◦ (AA Tau, Bouvier et al. detection of a jet in these stars. On the other hand, for sev- 1999), where as GM Aur has i = 54◦ (Simon et al. 2000). eral stars known to be jet driving sources we did not detect As discussed in this paper, the disk origin for CoKu Tau 1 neon emission. It is possible that in these cases the orienta- is difficult to ascertain and could be attributed to the bipolar tion and width of the slit used prevented us from detecting jet. Interestingly, Cox et al. (2005) reports the presence of a jet neon emission at large velocities. in AA Tau. Although Najita et al. (2009) interprets the broad – Lines consistent with disk emission. This is possibly the case (FWHM=70 km s−1) [Ne II] line as due to the disk, a similar of CoKu Tau 1 since the line is centered at the stellar velocity, situation as in CoKu Tau 1 could occur, and the emission could has a symmetric profile and large FWHM ∼ 55 km s−1. The be due to a bipolar jet in AA Tau. However, in the case of GM line also presents wings extending toward velocities close to Aur, its moderate inclination, its transitional disk status, and the 100 km s−1. The emission of the fast rotating gas is likely absence of a reported jet all suggest that the emission may really coming from regions close to the star. However, an interpre- come from the disk. In any case, the X-ray luminosities of the tation of the line due to the bipolar jet cannot be excluded disk sources are of the order of 1030 erg s−1, sufficient to effec- and may, in fact, be better in view of the high [Ne II] lumi- tively heat the disk and to be responsible for the neon emission. nosity in CoKu Tau 1. Different studies suggest that soft X-rays can drive power- ful photoevaporativewinds that can disperse the disk effectively. For three stars in the sample, optical observations with Observationally, these winds translate in emission lines show- UVES allowed the determination of the radial velocity, a cru- ing a small blueshift. These winds are stronger, and are effec- cial measurement for determining the line shifts. The profiles of tive once the mass accretion rate has fallen to values lower than the forbidden lines detected in the optical spectra were compared −8 −1 30 −1 10 M⊙ yr for an X-ray luminosity LX ∼ 2 × 10 erg s . with the profile of the [Ne II] line to better constrain the emis- Out of 12 targets from Sacco et al. (2012), ten show evidence sion mechanism. In general we found a good agreement between of small blueshifts within 18 km s−1of the stellar velocity. Only the profiles of the optical forbidden lines and the [Ne II] lines, two targets were classified as Class II sources, while the rest was indicating a common emitting mechanism. Studies that combine classified as transition or pre-transition disk sources. In our sam- observations in the two bands need to be done in a more system- ple, FS Tau A and V892 Tau also show a blueshift, and three atic way. additional sources show such blueshifts in Pascucci & Sterzik Combining our results with previous studies based on high- (2009). Interestingly, Sacco et al. (2012) found evidence that the spectral and spatial resolution of neon, we attempt to extract FWHM of the detected lines in their sample increased with in- more general conclusions on the emitting mechanism, keeping creasing blueshift. Our sample does not show this trend, with in mind that the sample is incomplete and biased toward large the majority of lines with FWHM around 26-27 km s−1, except neon luminosities. For stars with neon emission compatible with for CoKu Tau 1 that is much broader and EC 92 which is nar- disk emission and photoevaporative winds, a relation between rower but slightly above the VISIR instrumental resolution of [Ne II] and X-ray luminosities is difficult to see. Sacco et al. −1 10 km s . In fact, a plot of FWHM vs vpeak from both our and (2012) found a correlation between the [Ne II] line FWHM and Sacco’s data sets shows no evidence of a correlation. The high the peak velocity, but our study does not confirm this trend. In number of [Ne II] lines consistent with photoevaporative winds fact a combination of Sacco et al.’s and our data sets shows no by Sacco et al. (2012) could suggest that photoevaporationof the trend. disk is an effective mechanism. 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P. 2000, VizieR Online Data Catalog, 336, 50090 Glassgold, A. E., Najita, R., J., & Igea, J. 2007, ApJ, 656, 515 14 Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations Table 5. Properties of the optical UVES lines for CoKu Tau 1, FS Tau A, and V853 Oph. The [O I] lines at λ6300 and λ6363 of V853 Oph were fitted using the sum of two Gaussians to account for the low and high-velocity components (LVC and HVC), while flux and equivalent width were calculated for the sum of the two components. Line Wavelength Center FWHM Flux (×10−15)EW (Å) (kms−1) (km s−1) (erg s−1cm−2) (Å) CoKu Tau 1 Hα 6562.819 10.2(0.8) 103.5(0.8) 5.86 (0.1) −40.0 He I 5015.678 ...... < 1.0 > −14.0 He I 5875.621 ...... < 0.01 > −0.1 He I 6678.151 ...... < 0.01 > −0.1 Li I 6707.760 5.1(1.8) 35.3(3.8) 0.10 (0.1) 0.7 [N II] 6548.050 1.3(0.8) 85.4(3.9) 0.41 (0.1) −2.8 [N II] 6583.450 8.5(0.8) 77.3(1.6) 1.33 (0.1) −9.1 [O I] 5577.339 ...... < 0.06 > −0.1 [O I] 6300.304 4.6(0.8) 58.2(0.9) 3.21 (0.1) −21.9 [O I] 6363.777 3.9(0.8) 54.6(1.6) 1.02 (0.1) −7.2 [S II] 6716.440 7.0(0.8) 53.5(0.8) 0.85 (0.1) −5.7 [S II] 6730.815 7.6(0.8) 57.4(0.6) 2.01 (0.1) −13.7 Fe II 5018.434 ...... < 0.1 > −2.0 Fe II 5169.030 ...... < 0.05 > −0.7 Fe II 5197.577 ...... < 0.07 > −1.0 Fe II 6432.680 38.1(4.4) 292.8(12.3) 0.9(0.1) −5.3 FS Tau A Hα 6562.819 −6.0(0.4) 71.8(1.3) 832(5) −16.1 He I 5015.678 ...... < 1.4 > −0.2 He I 5875.621 1.9(0.7) 41.2(1.9) 3.2(0.6) −0.5 He I 6678.151 ...... < 129 > −2.5 Li I 6707.760 4.9(0.2) 30.8(0.4) 20.7(5.2) 0.4 [N II] 6548.050 −1.2(0.2) 30.6(0.6) 47.2(5.2) −1.0 [N II] 6583.450 −3.4(0.2) 31.8(0.4) 181(5) −3.5 [O I] 5577.339 −0.6(0.8) 29.1(2.0) 3.8(0.6) −0.6 [O I] 6300.304 −0.6(0.2) 26.0(0.4) 295(5) −5.7 [O I] 6363.777 −1.3(0.2) 25.1(0.5) 101(5) −2.0 [S II] 6716.440 −0.9(0.2) 26.4(0.5) 97.9(5.2) −1.7 [S II] 6730.815 −0.0(0.1) 24.6(0.3) 181(5) −3.5 Fe II 5018.434 ...... < 1.0 > −0.2 Fe II 5169.030 ...... < 0.2 > −0.03 Fe II 5197.577 18.2(0.6) 25.2(1.7) 3.2(0.6) −0.5 Fe II 6432.680 ...... < 2.1 > −0.04 V853 Oph Hα 6562.819 1.5(0.3) 117.5(0.8) 235.2(0.8) −30.3 He I 5015.678 1.8(0.3) 21.4(0.7) 6.4(1.4) −0.5 He I 5875.621 3.0(0.1) 36.1(0.5) 35.0(1.4) −2.6 He I 6678.151 2.8(0.2) 17.8(0.9) 7.6(0.8) −1.0 Li I 6707.760 5.6(0.2) 22.0(1.6) 3.1(0.8) 0.4 [N II] 6548.050 ...... < 0.1 > −0.02 [N II] 6583.450 −41.7(0.8) 34.3(1.9) < 1.7 > −0.2 [O I] 5577.339 −4.0(0.8) 49.6(1.9) 6.5(1.4) −0.5 [O I] (HVC) −32.1(0.1) 32.8(0.1) 6300.304 13.2(0.8) −1.7 [O I] (LVC) −2.8(0.1) 18.6(0.1) [O I] (HVC) −24.0(0.1) 26.9(0.1) 6363.777 3.9(0.8) −0.5 [O I] (LVC) −3.9(0.1) 11.2(0.1) [S II] 6716.440 ...... < 1.6 > −0.02 [S II] 6730.815 −37.1(0.5) 26.0(1.1) 1.9(0.8) −0.2 Fe II 5018.434 1.6(0.2) 14.9(0.5) 5.4(1.4) −0.4 Fe II 5169.030 0.9(0.1) 13.4(0.2) 6.5(1.4) −0.5 Fe II 5197.577 ...... < 1.2 > −0.1 Fe II 6432.680 ...... < 0.1 > −0.01 Note: The error in the center was calculated considering the contribution of the error in the Gaussian fit and in the stellar radial velocity. 15 Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations, Online Material p 1 Appendix A: Additional Material barycentric motion of the earth at the moment of the observa- tions to obtain the final radial velocity measurement. The radial A.1. VISIR transmission spectra velocities obtained with this method are presented in Table A.1, Figure A.1 provides the VISIR transmission spectra for both our where we also included the radial velocities from the literature, targets and the telluric standard. when available. Errors are reported between parentheses. For one object (V853 Oph) there is no previous measurement of the radial velocity, while for FS Tau A there are two measurements A.2. Radial velocities used in this study available in the literature, both having uncertainties larger than 5 km s−1. For FS Tau A and V853 Oph the precision achieved Since the stellar radial velocity is a key parameter in determin- in this work is < 1kms−1. Finally, due to the lower signal-to- ing the centroid of the emission lines, it is worth to explain the noise ratio obtained in the spectrum of CoKu Tau 1, fewer pho- choice of radial velocities used in this study. tospheric lines were detected. Therefore, the precision achieved For the stars located in the Taurus region with no mea- in the radial velocity is lower for this star (17.5 ± 2.4 km s−1) surement of the radial velocity available in the literature, we than that derived by White & Hillenbrand (2004), although our adopted the average radial velocity of Taurus, vrad = 16.0 ± −1 value is consistent. Therefore we used their radial velocity in this 0.4kms (Bertout & Genova 2006). We also use this value for paper. 12 = − the HerbigBe star V892Tau. The CO J 2 1 observationsby In addition, we obtained the v sin i for the three stars by Pani´c& Hogerheijde (2009) were likely dominated by extended comparing the observed spectra with rotationally broadenedsyn- emission from the cloud. A search through the Herbig & Bell thetic spectra (e.g., Bertone et al. 2008; M¨uller et al. 2011) of (1988) catalogue within 1′ of V892 Tau for radial velocities of Teff = 3850 K and log g = 4.5forCoKu Tau 1 andFS Tau A.For good quality also argued in favor of a radial velocity around V853 Oph the values used were T = 3370 K and log g = 4.5, − −1 eff 15 16km s for V892 Tau. the lines are spectrally unresolved. The results are reported in In addition, the radial velocities used for two stars Table A.1. (L1551 IRS5 and EC 92) are reported in the literature using the frame of the Local Standard of Rest (LSR), vLSR (Covey et al. 2006). In these cases the radial velocities were converted to vrad A.3. Lines detected in UVES spectra using the expression vrad = vLSR−(U⊙ cos l + V⊙ sin l) cos b−W⊙, where l and b are the coordinates of the star in the Galactic co- −1 −1 ordinate system, and U⊙ = 10.3kms , V⊙ = 15.3kms , and −1 W⊙ = 7.7kms come from Niinuma et al. (2011). A.2.1. Determination of the stellar radial velocity from UVES spectra To determine the radial velocity of our program stars, we used the optical spectra obtained by UVES. Optical spectra are popu- lated by a series of absorption lines from the stellar photosphere, where the lines are shifted due to the stellar motion with respect to the observer, the radial velocity. In order to determine the line shift, each spectrum was compared with a high-resolution syn- thetic spectrum (Bertone et al. 2008) of a star having the same spectral type as the star observed. Where an appropriate syn- thetic spectrum was not available, we used a synthetic spec- trum of similar spectral type as the star observed. For this pur- pose we used the interactive IDL-based software described in Carmona et al. (2010). This tool allows the synthetic and target spectra to be displayed, and to calculate the radial velocityofthe observed spectrum using the cross-correlation technique. The maximization of the cross-correlation function is a widely-used procedure to determine radial velocities (e.g., Tonry & Davis 1979; Allende Prieto 2007). If we have two arrays, S corre- sponding to the stellar spectrum and T the template spectrum, the cross-correlation between the two will be a new array C de- fined by the following expression: Ci = X Tk S k+i (A.1) k The maximum value of the cross-correlation function C will correspond to the element i = p where p is the shift in pixels between both the stellar spectra S and the template spectrum T. The position of the maximum of the function (the radial veloc- ity) and its error were calculated with a Gaussian fit. The ra- dial velocity measured by cross-correlation was corrected by the Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations, Online Material p 2 Table A.1. Radial velocities obtained from UVES spectra Name v sin i vradial vradial (km s−1) (km s−1) (km s−1) This work This work Literature Reference CoKu Tau 1 10 (3) 17.5 (2.4) 15.0(0.8) White & Hillenbrand (2004) FS Tau A 15 (5) 17.1 (0.1) 24 (7) Folha & Emerson (2000) 18 (5) Eisl¨offel & Mundt (1998) V853 Oph < 7 −8.9 (0.1) ... Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations, Online Material p 3 1.6 1.4 MHO 1 (2011-01-21) MHO 2 (2011-01-21) 1.4 V892 Tau 1.4 1.2 1.2 1.2 1.0 1.0 1.0 0.8 0.8 0.8 Normalized Flux 0.6 0.6 0.6 3.0 1.8 CoKu Tau 1 FS Tau A (2010-01-04) 4 SST042936+243555 1.6 2.5 3 1.4 2.0 1.2 2 1.5 1.0 1 1.0 0.8 Normalized Flux 0 0.6 0.5 1.6 1.2 XZ Tau 1.2 L1551 IRS 5 UY Aur A (2011-01-23) 1.4 1.0 1.0 1.2 1.0 0.8 0.8 0.8 0.6 Normalized Flux 0.6 0.6 0.4 0.2 1.6 2.5 UY Aur B (2011-01-23) 2.0 VZ Cha 3 RXJ1111.7-7620 1.4 1.5 1.2 2 1.0 1.0 0.8 0.5 1 0.6 0.0 Normalized Flux 0 0.4 -0.5 0.2 1.8 1.6 V853 Oph IRS 60 (2009-05-31) EC 92 (2009-05-31) 2.0 1.6 1.4 1.4 1.2 1.5 1.2 1.0 1.0 1.0 0.8 0.8 Normalized Flux 0.6 0.6 0.5 12.808 12.812 12.816 12.808 12.812 12.816 12.808 12.812 12.816 Wavelength (µm) Fig. A.1. VISIR transmission spectra. In black the spectra of the star and in red the spectrum of the telluric standard. We included one spectrum for the stars observed in two days. The spectra are presented before the barycentric and radial velocity correction to visualize the telluric absorption lines and the observed science and standard star/asteroid spectra. Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations, Online Material p 4 5 H alpha 1.0 He I 5015 2 He I 5876 He I 6678 0.8 2.0 4 1 0.6 1.5 3 0.4 0 1.0 0.2 2 -1 0.0 0.5 Normalized Flux 1 -0.2 -2 0.0 4 3 Li 6707 3.0 [N II] 6548 [N II] 6583 [O I] 5577 1.5 2 2.5 3 1 1.0 2.0 2 0 1.5 0.5 -1 Normalized Flux 1.0 1 -2 0.0 0.5 15 6 8 [O I] 6300 5 [O I] 6363 [S II] 6716 [S II] 6730 5 4 6 10 4 3 3 4 5 2 2 Normalized Flux 2 1 1 0 -100 0 100 3 Fe II 5018 Fe II 5169 2 Fe II 5197 Fe II 6432 0.4 5 2 1 4 0.2 1 3 0 0.0 0 2 Normalized Flux -1 -0.2 -1 1 -100 0 100 -100 0 100 -100 0 100 -200 0 200 v (km s-1 ) v (km s-1 ) v (km s-1 ) v (km s-1 ) Fig. A.2. Lines detected in the UVES spectrum of CoKu Tau 1. The spectrum was normalized to the continuum level. The fitted Gaussian profile is overplotted in green solid line. Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations, Online Material p 5 H alpha He I 5015 1.6 He I 5876 He I 6678 8 2.0 0.1 1.4 1.5 6 0.0 1.2 1.0 4 1.0 -0.1 Normalized Flux 0.5 2 0.8 0.0 -0.2 Li 6707 2.2 [N II] 6548 [N II] 6583 [O I] 5577 1.6 1.0 2.0 4 1.8 1.4 0.8 1.6 3 1.2 1.4 0.6 1.0 1.2 2 Normalized Flux 0.8 0.4 1.0 1 0.6 0.2 0.8 4 6 10 [O I] 6300 4 [O I] 6363 [S II] 6716 [S II] 6730 5 8 3 3 4 6 2 3 4 2 Normalized Flux 2 2 1 1 1 2.0 Fe II 5018 Fe II 5169 2.5 Fe II 5197 Fe II 6432 1.1 1.5 1.5 2.0 1.0 1.0 1.5 1.0 0.9 0.5 1.0 0.8 Normalized Flux 0.5 0.5 0.0 0.7 -100 0 100 -100 0 100 -100 0 100 -100 0 100 v (km s-1 ) v (km s-1 ) v (km s-1 ) v (km s-1 ) Fig. A.3. Lines detected in the UVES spectrum of FS Tau A. The absorption feature next to [S II] (λ6716) is the absorption line of CaI(λ6717). Baldovin-Saavedra et al.: On the origin of [Ne II] emission in young stars: VLT observations, Online Material p 6 H alpha He I 5015 4.0 He I 5876 2.2 He I 6678 3.5 2.5 3.5 2.0 3.0 3.0 1.8 2.0 2.5 2.5 1.6 1.4 2.0 1.5 2.0 1.2 1.5 Normalized Flux 1.5 1.0 1.0 1.0 1.0 0.8 Li 6707 1.15 [N II] 6548 1.3 [N II] 6583 1.6 [O I] 5577 1.0 1.10 1.2 1.4 1.05 0.8 1.00 1.1 1.2 0.6 0.95 1.0 Normalized Flux 0.90 1.0 0.9 0.4 0.85 2.5 [O I] 6300 [O I] 6363 [S II] 6716 1.4 [S II] 6730 1.4 1.2 1.3 2.0 1.1 1.2 1.2 1.0 1.1 1.5 1.0 1.0 0.9 Normalized Flux 1.0 0.8 0.9 3.5 1.2 2.5 Fe II 5018 Fe II 5169 1.4 Fe II 5197 Fe II 6432 3.0 1.1 2.0 2.5 1.2 1.0 1.5 2.0 1.0 1.5 0.9 Normalized Flux 1.0 0.8 1.0 -100 0 100 -100 0 100 -100 0 100 -100 0 100 v (km s-1 ) v (km s-1 ) v (km s-1 ) v (km s-1 ) Fig. A.4. Lines detected in the UVES spectrum of V853 Oph. The profile of [OI] λ6300 was fitted with two Gaussians to account for the high and low-velocity components observed.